Final answer:
FAA preferred routes can be found in the FAA's National Airspace System (NAS) database, which can be accessed through flight planning tools.
Step-by-step explanation:
FAA preferred routes can be found in the FAA's National Airspace System (NAS) database. This database contains information on all the preferred routes available for aircraft in the United States. It includes the departure airport, destination airport, and the specific route to be followed. Pilots can access this information through various flight planning tools such as the FAA's Flight Plan Service or third-party flight planning applications.